The number of foreign professors at North Korea's only private university has nosedived amid the strict enforcement of UN sanctions on Pyongyang, Radio Free Asia reported Thursday.

As of Tuesday, when this year's fall semester began, Pyongyang University of Science and Technology had 28 foreign professors, down 72.5 percent from the fall semester of the 2015 academic calendar, the US-based media outlet reported.

(AP)

They are from China, Singapore, Germany, Switzerland, the Netherlands, Britain and Canada, and it has yet to be confirmed whether any US professors work at the school, according to RFA.

A job advertisement for positions of English, Chinese and German professors in the 2019 spring semester, posted by the North Korean university on Wednesday, said that "applicants with US citizenships cannot be recruited at this time."

RFA attributed the sharp decrease to the impact of US sanctions on the North and a US measure to ban Americans from traveling to the North.

Starting September last year, the US government has prohibited Americans from traveling to North Korea, following the death of university student Otto Warmbier after he was imprisoned there for more than a year.

In May this year, North Korea released three US citizens who had been detained in North Korea, ahead of the historic summit between leaders of the United States and North Korea the following month. Two of the three -- Kim Sang-dok, who taught accounting at the university, and Kim Hak-song, who also worked for the university -- had been in custody since April and May of 2017, respectively, for allegedly committing "hostile acts" against Pyongyang.

Established by a South Korean foundation and North Korea's education ministry in 2010, the school needs to employ foreign professors as it provides all classes in English.

Meanwhile, the number of freshmen at the university fell 24 percent from three years ago to 114, including 18 female students, in the 2018 fall semester. (Yonhap)